• Economic and Environmental Geology
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• v.37 no.1
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• pp.73-86
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• 2004

In order to estimate the post-ingestion bioavailability of heavy metals and to assess the risk of adverse health effects on human exposure to toxic heavy metals, environmental geochemical surveys were undertaken around the Dogok Au-Ag-Cu and the Hwacheon Au-Ag-Pb-Zn mine sites. Human risk assessment of toxic heavy metals was performed with the results of the SBET(simple bioavailability extraction test) analysis for soil and chemical analytical data for crop plant and water. Arsenic and other heavy metals were highly elevated in tailings from the Dogok(218 As mg/kg, 90.2 Cd mg/kg, 3,053 Cu mg/kg, 9,473 Pb mg/kg, 14,500 Zn mg/kg) and the Hwacheon(72 As mg/kg, 12.4 Cd mg/kg. 578 Pb mg/kg, 1,304 Zn mg/kg) mines. These significant concentrations can impact on soils and waters around the tailing dumps. The quantities of As, Cd and Zn extracted from paddy soils in the Hwacheon mine using the SBET analysis were 55.4%, 20.8% and 26.4% bioavailability, respectively, and for farmland soils in the Dogok mine, 40.8%, 37.6% and 33.0% bioavailability, respectively. From the results of human risk assessment, HI(Hazard Index) value exceeded 1.0 for As in the Hwacheon mine and for Cd in the Dogok mine. Thus, toxic risks for As and Cd exist via exposure(ingestion) of contaminated soil, water and rice grain in these mine sites. The cancer risk for As by the consumption of rice and groundwater in the Hwacheon mine area was 8E-4 and 1E-4, respectively. This risk level exceeds the acceptable risk(1 in 100,000) for regulatory purpose. Therefore, regular ingestion of locally grown rice and ground-water by the local population can pose a potential health threat due to long-term arsenic exposure.

• Korean Journal of Ichthyology
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• v.35 no.4
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• pp.224-235
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• 2023

South Korea is the only divided nation globally, marked by a military demarcation line establishing demilitarized and civilian control zones, ensuring national security. Consequently, these areas exhibit relatively minimal ecological disruption compared to other regions. However, the threat to safety persists due to the presence of unexploded ordnances and landmines, imposing significant constraints on ecological research. To address this, we conducted a comparative study utilizing eDNA analysis as a supplementary and alternative approach within three points of the "Road of Peace" - Inje, Yanggu, and Hwacheon courses, located within the civilian control zone. Direct surveys and indirect eDNA sampling were carried out in May, July, and September of 2022. Genetic material obtained from the samples underwent amplification, library preparation, MiSeq sequencing, and subsequent ASV generation for indirect analysis. These results were then compared with the findings of direct surveys. Our findings revealed the detection of eDNA for both observed species at the Yanggu-1 point, and for two out of four species at Yanggu-2. Hwacheon-1 displayed the detection of eDNA for one out of one observed species, whereas Hwacheon-2 yielded seven out of twelve, Hwacheon-3 showed four out of six, and all one observed species at Hwacheon-4 exhibited eDNA detection. Consequently, approximately 69% of the fish species identified through direct surveys were confirmed by indirect eDNA analysis. It is necessary to verify if certain fish species, such as the continental trout and catfish, have genetic information registered in the NCBI database. Additionally, it is believed that further marker development research utilizing different genetic sequences is essential. Given the limitations imposed by the hazardous nature of the surveyed civilian control zone, eDNA analysis proves to be a suitable supplement for fish research in the area.

• Journal of Bio-Environment Control
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• v.17 no.4
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• pp.325-329
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• 2008

This study was conducted to compare the postharvest physiological characteristics of 2 paprika cultivars; 'Special', 'Fiesta' grown in 2 regions: Chuncheon(plain region) and Hwacheon(semi-high land region), and by 2 cultural methods; soil and hydroponic(rock wool culture). Respiratory rate of paprika fruit was higher in soil culture, and ethylene production was higher in Chuncheon region of both cultivars. As the thickness of fruit flesh showed thicker in Hwacheon region and hydroponic culture, the firmness of fruit was in proportion to thickness. Vitamin C content was higher in red-cultivar, 'Special'. and in Chuncheon region. Soluble solids was higher in 'Special', but there was no different between cultural regions. The fruit of both cultivars was grown smaller in Chuncheon region, and the fruit shape of 'Fiesta' progressed faster in soil culture. The surface color of fruit was higher in Hwacheon, and although there was no significantly different between cultural method, both cultivars grown by hydroponics was shown vivid color. As above results, for the long term circulation and high quality of fruit, paprika may be cultivated by hydroponics in high-altitude region.

• Economic and Environmental Geology
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• v.9 no.1
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• pp.27-43
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• 1976

The flourite in Hwacheon, Hwanggangri and Keumsan district are major fluorite producing areas in Korea. The fluorite deposits of Hwacheon district are wholly fissure filling hydrothermal veins embedded in Precambrian gneiss and schists and Jurassic granites. Also some fluorite deposits are emplaced in felsite whose age is unknown. Emplacement of most fluorite veins of the district are controlled by EW fracture system. Fluorites are generally accompanied to chalcedonic quartz and also kaolinite, montmorillonite, dickite and calcite in parts. Vertical and lateral mineral zonings are not distinct. The fluorite deposits in the Hwanggangri district are wholly embedded in limestone and other calcareous sediments of Paleozoic Yeongweol Group. Most of the fluorite deposits belong to one of two categories which are steeply. dipping veins and gently dipping replacement deposits adjacent to Late Cretaceous(83-90mys) granite bodies. The strikes of fluorite veins of Hwanggangri district mostly occupy the fractures of $N30^{\circ}-40^{\circ}E$ and $N30^{\circ}-40^{\circ}W$ system. Fluorites are accompanied to calcite, milky quartz, chalcedonic quartz, and also montmorillonite, kaolinite in parts. But in some deposits, scheelite, various sulfide minerals and barite are accompanied. Emplacement of fluorite deposits are largely controlled by lithology and structures of this district. In some deposits fluorite veins gradate to scheelite veins and also telescoping of the mineral zones are found in this district. In the Keumsan district, fissure-filled fluorite veins and replacement deposits are mostly emplaced in limestone of Paleozoic Yeongweol Group, late Cretaceous quartz-porphyry, granite and sandstone. Some deposits are emplaced in Precambrian metasediments. Mineralogy and other characteristics of the deposits in this district is similar to those of Hwanggangri district. Fluid inclusion studies reveal the difference of salinities, $CO_2$ contents of ore fluid and temperatures during fluorite mineral deposition in the these districts. In Hwacheon district, ore-fluids were comparatively dilute brine and low $CO_2$ content. Filling temperatures ranges $104^{\circ}C$ to $170^{\circ}C$. In the Chuncheonshinpo mine, most deeply exploited one in this district, salinitles range 0.5-2. 2wt. % NaCl and filling temperatures range from $116^{\circ}C$ to $143^{\circ}C$. In the Hwanggangri district, ore fluids were complex and filling temperature ranges very widly. In the contact metasomatic fluorite deposits, ore fluid were NaCl rich brines with moderate $CO_2$ content and filling temperatures range from $285^{\circ}C$ to above $360^{\circ}C$. Fluids inclusions in tungsten and sulfide minerals bearing fluorite veins show high $CO_2$ content up to 31wt. %. Filling temperature ranges from $101^{\circ}C$ to $310^{\circ}C$. Fluids inclusions In mainly fluorite bearing veins were more dilute brine and low $CO_2$ contents. Filling temperatures range from $95^{\circ}C$ to $312^{\circ}C$. Filling temperature of fluid inclusions of Keumsan district are between $95^{\circ}C$ and $237^{\circ}C$. Data gathered from geologic, mineralogic and fluid inclusion studies reveal that fluorite mineralization in H wacheon district proceeded at low temperature with dilute brine and low $CO_2$ content. In Hwangganri district, fluorite mineralization proceeded by several pulse of chemically distinct ore fluids and formed the mineralogically different type of deposits around cooling granite pluton which emplaced comparatively shallow depth.

• Geophysics and Geophysical Exploration
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• v.16 no.4
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• pp.203-210
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• 2013

To look into site characteristics of the Hwacheon borehole seismic station, we analyzed property of earthquake and microtremor recorded on surface and borehole seismometers. Acoording to analysis result of microtremor, the surface-to-borehole energy ratio was approximately 15 times greater during the daytime than during the nighttime, and the surface-to-borehole ratios of spectral amplitudes as frequency increases. For earthquake data, amplitude spectra and dominant frequency were computed using surface and borehole data. As a result, small earthquakes with short distance recorded on surface seismometer peaked at 8 Hz, 46 Hz. This result corresponds to resonance frequencies (7.4 Hz, 46 Hz) calculated by H/V spectral ratio. We confirmed amplification effect by site characteristics of overburden. Background noise level was approximately 20,000 times smaller at borehole seismic station than surface seismic station. These results provide strong evidence for the superior recording of earthquakes using borehole seismometers instead of surface seismometers.

• Journal of the Korean association of regional geographers
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• v.9 no.3
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• pp.395-409
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• 2003

In this study the meaning and necessity for self-regulation in managing and organizing the national curriculum is researched in order to reflect the reality that the tide of regionalization appears apparently with globalism. Hwacheon is chosen and applied as an example region for selecting and forming a new learning content in geography education and teaching and learning that content. The regional geography should be learned in high schools according to the approach of regional textbooks being made and used now in primary and middle schools, and the contents of textbooks should be properly reorganized in accordance with the students' school ages rather than organized simply with enumerating geographic facts in a row. And the contents should be organized centering on the learners' daily living sphere. In addition, teaching-learning method should be taken into consideration according to the scale of the regions. Consequently, in this study small-scaled area was chosen as a learning content, laying stress on daily lives within the living zone, and therefore field work is considered as a learning method.

• Korean Journal of Plant Resources
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• v.22 no.2
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• pp.159-179
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• 2009

This study was carried out to investigate the distribution of vascular plants and their usefulness in Mt. Ilsan (Hwacheon-gun, Gangwon-do). The vascular plants were summarized as 496 taxa; 91 families, 295 genera, 422 species, 1 subspecies, 58 varieties, and 15 forma. Among the investigated 496 taxa, 17 Korean endemic, nine rare, and one endangered plants were included. Based on the list of the species of specially designated plants by the Ministry of Environment, 66 taxa including Hanabusaya asiatica and Aconitum koreanum were recorded in the investigated area. The naturalized plants were identified as 27 taxa and the percent of naturalized plant species(PN) was 5.4% of all 496 taxa vascular plants. Usage of 496 taxa were consists of 201 taxa(40.5%) of edible plants, 168 taxa(33.9%) of medicinal plants, 69 taxa(13.9%) of pasture plants, 61 taxa(12.3%) of ornamental plants, 17 taxa(3.4%) of timber plants, 16 taxa(3.2%) of fiber plants and 4 taxa(0.8%) of industrial plants.

• Proceedings of the Plant Resources Society of Korea Conference
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• 2019.04a
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• pp.90-90
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• 2019

This study was carried out to investigate the vegetation and vegetation structure of Mt. Man in Hwacheon Gun from April to October 2018. The survey site is located in the northern part of South Korea where the climate is similar to that of North Korea. The purpose of this study is to provide basic information for efficient ecological forest management after unification. A total of 341 vascular plant taxa are recorded, representing 221 genera, 4 subspecies, 42 varieties and 6 forms in 84 families. Rare species, including Crataegus komarovii and Amitostigma gracile are found across 10 taxa; 8 families, 10 genera, 9 species, 1 variety. Naturalized Plants, including Ambrosia artemisiifolia and Erigeron annuus found across 11 taxa; 6 families, 10 genera, 11 species. Dominant tree species of the tree layer based on the highest importance values were: Quercus mongolica (23.47%), Larix kaempferi (11.43%), Fraxinus rhynchophylla (8.30%), in the subtree layer were: Lindera obtusiloba (11.38%), Acer pictum subsp. mono (11.33%), Fraxinus rhynchophylla (9.80%) and in the shrub layer were: Lindera obtusiloba (10.22%), Fraxinus rhynchophylla (8.43%), Rubus crataegifolius (8.00%), in the herb layer Pteridium aquilinum var. latiusculum (5.67%), Oplismenus undulatifolius (5.00%), Lysimachia clethroides (3.49%) respectively. The species diversity of Mt. Man was 1.1764 in the tree layer, 1.2403 in the subtree layer, 1.4135 in the shrub layer, and 1.7416 in the herb layer. In conclusion, if we utilize the flora and vegetation structure surveyed in Mt. Man, we can effectively manage the degraded forests with similar altitudes and climate zones in North Korea.

• Korean Journal of Heritage: History & Science
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• v.53 no.4
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• pp.250-273
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• 2020

The three-story stone pagodas in Hyeon-ri and Hwacheon-ri,Yeongyang Gyeongsangbuk-do are stone pagodas that exhibit the typical style of Unified Silla. The two pagodas are believed to have been built in the mid- and late 9th centuries at the latest, considering the style of the three-story roof stone on top of the double-tier base. This is also confirmed by the reliefs carved at the base and the first-story of the pagoda. The Four Heavenly Kings and the Twelve Zodiacal Animal Deities were first combined in the late 8th century in the stone pagoda at the Wonwonsa Temple Site, and the Eight Classes of Divine Beings was also the most popular carved pagoda reliefs in the 9th century. However, the two Yeongyang stone pagodas are characterized by a combination of the Four Heavenly Kings (1st story), the Eight Classes (top base), and the Twelve Zodiacal Animals (lower base), and the stone used for the pagoda consists of sedimentary rocks of the sandstone family, which comprise most of the geological strata in the Yeongyang area, rather than ordinary granite. The new combinations of the three types of guardian deities and the Eight Classes changed from seated to standing poses is interpreted as an attempt to enhance the Buddhist faith and cultural status of the Yeongyang area, along with the fact that the stone pagoda was built using local natural materials. The Eight Classes of the Yeongyang stone pagoda does not follow the two types of arrangement of the pagodas with the Eight Classes, but some of the deities have been relocated to a new location. Composed of AsuraGandharva on the east side, Naga-Mahoraga on the south, Deva-Garuda on the west, and Kimnara-Yaksa on the north, this form can be classified as a unique 'third layout of the Eight Classes' in the Yeongyang area. Such changes in the shape and posture of the reliefs reflect a new perception of the pagodas. The reason why the Gandharva and Yaksa statues were carved on the east and north sides, respectively, was because they were deemed subordinate to the Four Heavenly Kings, and the fact that the Naga and the Mahoraga were carved on the south side was presumed to have influenced the geographical location of the two pagodas on the northern side of Banbyeoncheon Stream. The Hyeon-ri and Hwacheon-ri three-story stone pagodas inherited the tradition of typical Unified Silla-period pagodas, while also bearing their own new regional characteristics.

• Journal of Welding and Joining
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• v.34 no.3
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• pp.1-5
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• 2016

At present, FSW(friction stir welding) process is being considered as an actual way for production of various industrial products. However FSW process involves high temperature and load on the tool during welding. These are make a difference between FSW machine and general machine tools. From this reason, development of FSW machine needs very careful consideration on stiffness of machine structure, spindle and moving axis including machine control system. In this study authors investigate on the trends of technology development of FSW machine in order to share the information for more extension of FSW technology with related researchers and engineers.